CVE-2026-31740 is a medium severity vulnerability in the Linux kernel's counter driver for the rz-mtu3 hardware. The issue arises because the dev member of the shared struct rz_mtu3_channel is overwritten by both the counter and PWM sub-drivers for channels 1 and 2, leading to a race condition. This causes the counter sub-driver to potentially perform runtime power management on the wrong device. The flaw is fixed by using the parent pointer assigned during probe instead of the shared dev member.